Platelet-derived growth factor-induced H2O2 production requires the activation of phosphatidylinositol 3-kinase
Platelet-derived growth factor-induced H2O2 production requires the activation of phosphatidylinositol 3-kinase
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DOI：
10.1074/jbc.275.14.10527
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发表时间：
2000-04-07
影响因子：
4.8
通讯作者：
Rhee, SG
中科院分区：
文献类型：
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作者：
Bae, YS;Sung, JY;Rhee, SG
血小板源性生长因子 (PDGF) 受体的自磷酸化会由于招募含有 Src 同源性 2 结构域的酶而触发细胞内信号级联，这些酶包括磷脂酰肌醇 S 激酶 (PI3K)、Pas 的 GTP 酶激活蛋白 (GAP)、蛋白酪氨酸磷酸酶 SHP-2 和 磷脂酶 C-yl (PLC-gamma 1)，针对特定的磷酸酪氨酸残基。现在已经在表达各种PDGF受体突变体的HepG2细胞中研究了这些不同效应物在PDGF诱导的H2O2产生中的作用。这些突变体包括激酶缺陷型受体和其中结合 PI3K（Tyr(740) 和 Tyr(751)）、GAP（Tyr（771））、SHP-2（Tyr（1009））或 PLC-gamma 1（Tyr（1021））所需的酪氨酸残基的各种组合突变为 Phe 的受体。 PDGF 未能增加表达激酶缺陷突变体或其中 PI3K 结合所需的两个 Tyr 残基仅被 Phe 取代的受体的细胞中 H2O2 的产生。相反，在表达GAP、SHP-2和PLC-γ1的结合位点全部突变的受体的细胞中，PDGF诱导的H 2 O 2 的产生略高于表达野生型受体的细胞中的H 2 O 2 的产生。仅 PI3K 结合位点就足以产生 PDGF 诱导的 H2O2。 PDGF 对 H2O2 产生的影响被 PI3K 抑制剂 LY294002 和渥曼青霉素或 Rad 显性失活突变体的过表达所阻断。这些结果表明，PDGF 诱导非吞噬细胞产生 H2O2 需要 PI3K 产物，并且 Rad 介导 PI3K 产物和推定的 NADPH 氧化酶之间的信号传导。
Autophosphorylation of the platelet-derived growth factor (PDGF) receptor triggers intracellular signaling cascades as a result of recruitment of Src homology 2 domain-containing enzymes, including phosphatidylinositol S-kinase (PI3K), the GTPase-activating protein of Pas (GAP), the protein-tyrosine phosphatase SHP-2, and phospholipase C-yl (PLC-gamma 1), to specific phosphotyrosine residues. The roles of these various effecters in PDGF-induced generation of H2O2 have now been investigated in HepG2 cells expressing various PDGF receptor mutants. These mutants included a kinase-deficient receptor and receptors in which various combinations of the tyrosine residues required for the binding of PI3K (Tyr(740) and Tyr(751)), GAP (Tyr(771)), SHP-2 (Tyr(1009)), Or PLC-gamma 1 (Tyr(1021)) were mutated to Phe. PDGF failed to increase H2O2 production in cells expressing either the kinase-deficient mutant or a receptor in which the two Tyr residues required for the binding of PI3K mere replaced by Phe. In contrast, PDGF-induced H2O2, production in cells expressing a receptor in which the binding sites for GAP, SHP-2, and PLC-gamma 1 were all mutated was slightly greater than that in cells expressing the wildtype receptor. Only the PI3K binding site was alone sufficient for PDGF-induced H2O2 production. The effect of PDGF on H2O2 generation was blocked by the PI3K inhibitors LY294002 and wortmannin or by overexpression of a dominant negative mutant of Rad. These results suggest that a product of PI3K is required for PDGF-induced production of H2O2 in nonphagocytic cells, and that Rad mediates signaling between the PI3K product and the putative NADPH oxidase.